Apparatus for distributing uniform gauge variations of plastic extruded film on windup rolls



Dec. 22, 1964 G. w. CHENEY 3,161,942

APPARATUS FOR DISTRIBUTING UNIFORM GAUGE VARIATIONS OF PLASTIC EXTRUDEDFILM ON WINDUF ROLLS Filed Jan. 3, 1961 2 Sheets-Sheet l IN VEN TOR.

Dec. 22, 1964 G. w. CHENEY 3,

APPARATUS FOR DISTRIBUTING UNIFORM GAUGE VARIATIONS OF PLASTIC EXTRUDEDFILM ON WINDUP ROLLS Filed Jan. 3, 1961 2 Sheets-Sheet 2 INVENTOR.

United States Patent ()fiiice Patented Dec. 22, 1964 AllAl lA'lllS FQRDESTRIBUTEWG UNlFQRM GAUGE VARlATltlb-IS 6F PLASTIC EX- TRUDED FILM 6NWINDUP ROLLS rant W. @heney, Midland, Mich, assignor to The Dow Chemical(Ionrpany, Midland, Mich a corporation of Delaware Filed .lan. 3, 1961,Ser. No. 80,153 7 Qlaims. (61. 29-212} This invention in a more specificsense, relates to apparatus for uniformly distributing gauge variationsof plastic extruded tubular film and sheeting on windup rolls.

It is found difiicult, if not impossible, to extrude plastic lm ofuniform microscopic thickness. Accordingly, in winding up extrudedplastic film on windup rolls, buildups are caused which produce highspots. As such high spots increase in size, the film is caused to bestretched,

vhich makes such film generally unuseable.

To avoid film spoilage which may be caused by such build-up, onesolution has been to rotate the extrusion die, or the pinch rollerstogether with the winding means, about the axis of the tubing as it isbeing extruded from the die. By way of example of such practice,reference may be made to Patent No. 2,844,846, issued July 29, 1958.

The apparatus of the present invention represents an improvement oversuch known arrangements for plastic film windup. More particularly, theapparatus of the present invention is not only of simplifiedconstruction insofar as only the windup mechanism is rotated, butcontinuous slitting of an extruded tube for winding on two rolls isachieved at the same time. An important feature of the disclosedembodiments of the invention resides in the use of a tube spreadingmeans which is positioned within an extruded tube, and is supported forrotation within the tube without causing twisting of the tube.

The main object of the present invention is to provide apparatus foruniformly distributing gauge variations of plastic extruded tubular filmand sheeting on windup rolls.

A more specific object is to provide apparatus for uniform distributionof gauge variations of plastic extruded tubular film on windup rollswhich apparatus is of simplified construction.

Another object of the present invention is to provide apparatus forslitting a plastic tubular film in such manner as to achieve uniformdistribution of gauge variations of the cut film on windup rolls.

These and further objects and features of the invention will become moreapparent from the following description and accompanying drawingswherein:

FIG. 1 is a schematic elevation view illustrating an arrangementincorporating the apparatus of the invention;

FIG. 2 is a View generally as seen along line 22 in FIG. 1;

FIG. 3 is a view similar to PK}. 1, but showing a modified embodiment ofthe invention; and

FIG. 4 is a fragmentary perspective view of a portion of the arrangementof FIG. 3.

Referring now to the drawing, and more particularly to F165. 1 and 2,the numeral ill identifies the die head of apparatus designed to extrudea plastic tube 12, which is inflated by air to form an elongated bubble,as illustrated. A plurality of rollers 14 are arranged to causeflattening of the bubble, after which the flattened tube passes betweena pair of pinch rollers 16 and over a guide roller 18. The axis ofrollers in and 13 are fixed in parallel relation.

A windup assemblage 2d includes a circular turntable,

or platform 22 mounted upon wheels 23, which run in a grooved circulartrack 24 supported upon the floor 26. A rubber drive wheel 28,frictionally engages the peripheral edge of the platform 22, said drivewheel being rotatable by an electric motor S ll, connected to the wheelby suitable reduction gear mechanism 32. The motor 30 may beirreversible, or may be of the reversible type, in which event, switchmeans (not shown) should be provided to cause oscillating movement ofthe turntable 22 through a given number of degrees, and at a given rateof speed as required for satisfactory operation under specificconditions.

Mounted upon the turntable 22 is a frame means 32 adapted to removablysupport a pair of windup rolls 34 in parallel spaced relation. A motormeans 36, is adapted to rotate said rolls 34 by suitable drive beltmeans as shown, whereby the rolls will be wound as required. Rotatablysupported by the frame means 32, are parallel spaced rollers 3% betweenwhich the extruded tube 312 is arranged to pass. Positioned within thetube 12 is a floating spreader assemblage 40, which includes a framemeans 42 supporting tube crease reforming rollers 44, two pair ofrollers 46 adapted for rotation by virtue of contact with the rollers 38through the tubing 12, and a pair of weight means 48. The weights 48maintain the assemblage 40 in upright position within the tubing 12, andresult in sufficient pressure between the rollers 46 and rollers 33%, sothat rotation of the rollers 38 in a horizontal plane, will causerotation of the assemblage as within the tube 1.2 and without rotationof the tube. Such action will result in reforming of the two edgecreases of the tube 12, whereby the new edge creases will be in spiralrelationship to a fixed longitudinal centerline of the tube 12, beforeit passes the assemblage iii. In other words, the platform 22 and windupmechanism is rotated about the tubular film 12. A roller 59 is supportedby the frame means 32, while a pair of trimming wheels 52 is arranged inabutment with the roller 59 for cutting the edges of the tube 12 to formtwo sheets, which are separately wound on the rolls 34. Rollers 54-,supported by the frame means 32, are arranged to direct one of the cutsheets to a roller 34. If so desired, the cut sheets may be fed on onlyone roll, and also, the trimming wheels may be omitted so that the tubeis wrapped in uncut condition.

It will be seen from the foregoing that as the turntable 22 is rotated,the reformed creases of the tube 12, developed by the floating spreader40, will be severed by the trimming wheels 52, so that gauge variationsin the sheets formed from the tubing will be distributed over the fullwidth of a windup roll, and build-ups will be avoided.

A modified embodiment of a windup assemblage till of the invention, isillustrated in FIGS. 3 and 4. For the sake of simplicity, the samenumerals are used to identify like parts described in connection withthe windup assemblage 2h.

The windup assemblage so has a frame means d2 which differs mostly fromthe frame means 32, in that a pair of upright sloping braces 64 areprovided, which support a rod 66 therebetween, as best seen in FIG. 4.The rod as supports a slitter assemblage including two pairs of upwardlyextending arms 68, each of which support a wheel 7%? adapted to engage acreased inner edge of the folded plastic tube 12, and to cause areformation of the tube edge crease. A knife blade '72 is supported inhorizontal position below the wheels "ill, the ends of the knife bladeextending beyond the edges of the tubing 12. The knife blade '72, seversthe tubing into two sheets which are directed to the windup rolls 34. Itwill be seen that as the turntable 22 is rotated, the windup assemblageas, will be rotated relative to the tubing 12, so that the knife a,blade 72 will cut the tubing along edges which are in spiral relation toa fixed longitudinal centerline of the tubing. In such manner, any gaugevariations of the tubing will be distributed over the full width of awindup roll, and build-ups will be avoided.

The invention has so far been illustrated with respect to thepreparation of fiat film sheet from tubular stock. There are uses fortubular film, however, and the spiral redistribution of gauge variationherein described is as advantageous in preparing level Wound rolls ofuncut, flattened tubular film as in the described preparation of flatsheets. In applying the invention to such purpose, an apparatusembodying the principles shown in FIG. 1 is used, but the trimmingwheels 52 are disengaged from the flattened tube supply, and the productis Wound on a single roll 34.

From the foregoing it will be seen that the described embodiments willmeet the objectives of the invention as hereinbefore set forth.

The foregoing description has been given in detail without thought oflimitation since the inventive principles involved are capable ofassuming other forms without departing from the spirit of the inventionor the scope of the following claims.

What is claimed is:

1. Apparatus for uniformly distributing gauge variations of plasticextruded tubular film on windup rolls comprising, a rotatable platform,a frame means mounted upon said platform, a pair of windup rollssupported by said frame means, means to cut the tubular film into twosheets each of which will be wound upon a windup roll, and tubespreading means positioned within the tubular lm and supported by saidframe means for rotation therewith.

2. Apparatus for uniformly distributing gauge variations of plasticextruded tubular film in windup rolls comprising, a rotatable platform,a frame means mounted upon said platform, a pair of power driven winduprolls supported by said frame means, a pair of rollers supported inspaced parallel relation by said frame means, a floating spreaderadapted to be positioned within said tubular film and to be supported bysaid rollers, and trimming Wheels carried by said frame means to cut theedges of said tubular film after it passes the floating spreader to formseparate sheets each of which will be wound upon a windup roll.

3. Apparatus for uniformly distributing gauge variations of plasticextruded tubular film on windup rolls comprising, a rotatable platform,a frame means mounted upon said platform, a pair of power driven winduprolls supported by said frame means, a pair of rollers supported inspaced parallel relation by said frame means, a floating spreaderassemblage adapted to be positioned within said tubular film and to besupported by said rollers, said spreader assemblage including creasereforming rollers which engage inner creased edges of the tubular film,and trimming wheels carried by said frame means to cut the reformededges of said tubular film after it l passes the floating spreader toform two sheets each of which will be wound upon a wiudup roll.

4. Apparatus for uniformly distributing gauge variations of plasticextruded tubular film according to claim 3, wherein said floatingspreader assemblage includes Weight means to positionally maintain theassemblage in operative position within the tubular film.

5. Apparatus for uniformly distributing gauge varia tions of plasticextruded tubular film on windup rolls comprising, a rotatable platform,a frame means mounted upon said platform, a pair of power driven winduprolls supported by said frame means, a sli-tter assemblage carried bysaid frame means and positionable within the tubular film, said slitterassemblage including crease reforming rollers which engage inner creasededges of the tubular film, and a cutting means mounted upon the framefor slitting the tubular film into two sheets each of which will bewound upon a windup roll.

6. Apparatus for uniformly distributing gauge variations of plasticextruded tubular film on windup rolls comprising, a rotatable platform,a frame means mounted upon said platform, a pair of power driven winduprolls supported by said frame means, a pair of rollers supported inspaced parallel relation by said frame means, a slitter assemblagecarried by said frame means and positionable within the tubular film,said slitter assemblage including crease reforming rollers which engageinner creased edges of the tubular film and reform the creased edges ofthe tubular film as the slitter assemblage is rotated, said slitterassemblage further including a knife blade for slitting the tubular filmalong the reformed creased edges to provide two sheets each of which isguided by one of the parallel arranged rolls into a Windup roll.

7. Apparatus for uniformly distributing gauge variations of plasticextruded tubular film on windup rolls comprising, a rotatable platform,a frame means mounted on said platform, windup roll means supported bysaid frame, means to supply tubular film to the apparatus, and tubespreading means positioned Within the tubular film and supported by saidframe means for rotation therewith.

References Cited in the file of this patent UNITED STATES PATENTS2,659,931 Dettrner Nov. 24, 1953 2,720,680 Gerow Oct. 18, 1955 2,844,846Kronholm July 29, 1958 2,923,194 Ambler et al Feb. 2, 1960 2,943,356Rasmussen l July 5, 1960 3,009,208 Pirot Nov. 21, 1961 3,022,543 Bairdet al. Feb. 27, 1962 3,079,636 Aykanian Mar. 5, 1963 3,088,167 CorbettMay 7, 1963 FOREIGN PATENTS 203,916 Australia Q. Nov. 1, 1956 813,028Great Britain May 6, 1959 571,392 Canada Feb. 24, 1959

1. APPARATUS FOR UNIFORMLY DISTRIBUTING GAUGE VARIATIONS OF PLASTIC EXTRUDED TUBULAR FILM ON WINDUP ROLLS COMPRISING, A ROTATABLE PLATFORM, A FRAME MEANS MOUNTED UPON SAID PLATFORM, A PAIR OF WINDUP ROLLS SUPPORTED BY SAID FRAME MEANS, MEANS TO CUT THE TUBULAR FILM INTO TWO SHEETS EACH OF WHICH WILL BE WOUND UPON A WINDUP ROLL, AND TUBE SPREADING MEANS POSITIONED WITHIN THE TUBULAR FILM AND SUPPORTED BY SAID FRAME MEANS FOR ROTATION THEREWITH. 